The present invention concerns an agricultural greenhouse comprising a metallic frame which supports transparent covering means having asymmetrical slopes.
Such greenhouses are known, and the asymmetrical roof structure assures an optimum effect of sunlight by directing the greater slope southward. Roofs of this type are formed by glass panels which are supported by metallic structures. Despite its physical and optical qualities, such as solution has considerable drawbacks.
Glass panels are heavy, and their transportation, handling and putting into place are long and difficult operations. To attain tightness at the levels of the ridges and the gutters of such a roof, joints and sections of a complex and costly construction are needed, the setting up of which is delicate and takes a long time.
It has already been proposed to replace the glass panels by smooth panels of transparent plastic; but the rigidity of such panel is insufficient for an acceptable economic solution. Providing tight joints in such a case is even more difficult than in the case of glass panels.
On the other hand, when plastic panels are utilized which are made rigid by ribs or undulations, all the advantages of an asyymetrical structure with respect to optimum sunlight exposure are lost.